1. Field of the Invention
The present invention relates generally to disk drives and more particularly to a method, apparatus, and computer readable program product for improving the performance of hard disk drive servomechanisms.
2. Description of the Related Art
Hard disk drives include a plurality of magnetic transducers that can write and read information by magnetizing and sensing the magnetic field of a rotating disk(s), respectively. The information is typically formatted into a plurality of sectors that are located within an annular track. There are a number of tracks located across each surface of the disk. A number of vertically similar tracks are sometimes referred to as a cylinder. Each track may therefore be identified by a cylinder number.
Each transducer is typically integrated into a slider that is incorporated into a head gimbal assembly (HGA). Each HGA is attached to an actuator arm. The actuator arm has a voice coil located adjacent to a magnet assembly which together define a voice coil motor. The hard disk drive typically includes a driver circuit and a controller that provide current to excite the voice coil motor. The excited voice coil motor rotates the actuator arm and moves the transducers across the surfaces of the disk(s).
When writing or reading information, the hard disk drive may perform a seek routine to move the transducers from one cylinder (track) to another cylinder. During the seek routine the voice coil motor is excited with a current to move the transducers to the new cylinder location on the disk surfaces. The controller also performs a servo routine to insure that the transducer is at the center of the track.
The assignee of the present invention has introduced disk drives that utilize a sinusoidal seek algorithm where the transducer is moved according to a sinusoidal trajectory.
The present invention comprises a method, apparatus, and computer program product for a hard disk drive. In one embodiment, the apparatus comprises a disk which has a surface, a spindle motor to rotate the disk, a transducer to write information onto the disk and read information from the disk, an actuator arm to move the transducer across the surface of the disk, and a controller. The controller, in response to a command to seek from a first track to a second track, can determine a seek length from the first track to the second track, determine a seek time based on the seek length, scale the seek time in response to a velocity error between a calculated velocity and a design velocity for the seek length, and control the actuator arm to move said transducer across said disk surface from the first track to the second track using an acceleration trajectory.